As the amount of data processed by computer devices or the like increases, data transmission using electrical signals has been replaced with data transmission using optical signals. For example, some of transceivers, other various devices and apparatuses, or the like carry out transmission and reception of data (signal) by using optical signals. In recent years, development of a technology, referred to as silicon photonics, in which a transmission unit, a reception unit, an optical wiring unit of such devices and apparatuses are formed on a silicon substrate has advanced.
An example of an integrated light source that is formed on a silicon substrate is disclosed in PTL 1. In PTL 1, an optical component is disclosed that includes a first optical waveguide, a second optical waveguide that is optically-coupled with the first optical waveguide through a first optical coupler and a second optical coupler individually and composes a Mach-Zehnder interferometer with the first optical waveguide, a first heater that is disposed on at least one of the first optical waveguide and the second optical waveguide between the first optical coupler and the second optical coupler, and a semiconductor laser that is optically-coupled with an input end of the first optical waveguide, and in which the first and the second optical waveguides, the first heater, and the semiconductor laser are integrated on an identical substrate. With such a configuration, the optical component in PTL 1 is capable of achieving more light output that enables power control as desired with a small number of semiconductor lasers used.
Another example of the integrated light source formed on a silicon substrate is disclosed in NPL 1. In NPL 1, a structure of a hybrid integrated light source in which a laser diode array with a high output power is mounted on a silicon wire waveguide platform is disclosed. The integrated light source disclosed in NPL 1 has a transmission unit that employs an external modulation system, making it possible to use CW (Continuous Wave) light and form a laser diode array having a single electrode, and, thus, it is possible to narrow the pitch of a laser diode array to one-tenth or narrower, compared with a case in which each laser diode is individually driven as in conventional cases (for example, a laser diode array formed under the assumption of optical fiber connection has a pitch of 250 to 300 μm).